WASHINGTON (CNN) -- Iraqi Shiite fighters are now been trained inside Iran as assassination squads, the U.S. military has told the Iraqi government.

A U.S. military spokesman in Baghdad confirmed details Friday. The story was first reported by The Associated Press. The official said the details are being made public in part to pressure Iran to stop the training.

The official confirmed that the training was being conducted by Iran's Quds force and elements of Lebanese Hezbollah at four locations inside Iran: Qom, Tehran, Ahvaz and Mashhad.

The United States this week gave the Iraqi government a list of the expected targets of the assassination squads, which would include Iraqi judges, Iraqi government officials and U.S. and Iraqi troops.

The information came from interrogation of captured fighters and other sources the official would not describe further.